Grinding lobed forms



Jan 1, 1952 M. H.ARMs

GRINDING LoBED FORM 5 Sheets-Sheet l Filed April 5, 1949 A a Il Jan. 1, 1952 M. H. ARMS 2,580,989

GRINDING LOBED FORM Filed April 5, `1949 5 Sheets-Sheet 2 Jan. 1, 1952 M. H. ARMS GRINDING LOBED FORM Filed April 5, 1949 5 Sheets-Sheet 5 ifa/027?? Mii/a JZ VW `I an. 1, 1952 M H, ARMS 2,580,989

GRINDING LOBED FORM Filed April 5, 1949 ,-5 Sheets-*Sheet .4

Jan. 1, 1952 M. H. ARMS GRINDING LOBED FORM 5 Sheets-Sheet 5 Filed April 5, 1949 Patented Jan. 1, 1952 GRINDING LOBED FORMS Merton H. Arms, Springfield, Vt., assignor 'to Bryant Chucking Grinder Company, Springfield, Vt., a corporation of Vermont Application April 5, 1949, Serial No. 85,547

Where high torque transmission between shafts and parts carried thereby isrequired, it has been found desirable in some instances to dispense with the use of keys or splines for securing the parts to the shaft in view of the relative weakness of this type of securement, and instead to make use of shafts having lobed shaped cross sectional contours engaged in openings of mating contour through the carried parts.

An object of this invention is to facilitate accurate shaping of the shaft and mating parts to such lobed contour. Commonly a three-lobed contour has been employed, though in its broader aspectsthis invention is applicable to the production of shapes having any desired number of lobes as will later appear. 1 This invention has particular utility where hardparts are employed when grinding to shape is indicated.

The work, whether internal orl external, is arranged to be presented to a rotary tool, such as a grinding wheel, andmoved in directions transverse to its axis so controlled that when presented to the tool the latter describes the desired lobed contour with relation to the work piece. Claims generic to this Ageneral method are contained in the-application for United States Letters Patent led February 13, 1949, Serial No. 77,183, by Philip C. Durland.

For a complete understanding of this invention, reference may be had to the accompanying drawings in which Figure 1 is a sectional View of a machine for grinding internal three-lobed forms, the section being taken on line I-I of Figure 4.

Figures 2 to 5, inclusive, are `sectional views on the correspondingly numbered section lines of Figure 1.

Figure 6 is a fragmentary top plan view showing the relation of an external grinding wheel to lobed work.

Figure '7 is a detail sectional view on line l-l of Figure 6.

Figure 8 is a fragmentary sectional view on line 'ei-8 of Figure 1, but showing the grinding wheel in grinding position.

Figures 9 and 10 are views similar to Figure 8, but showing different relative positions between the grinding wheel and the work piece, the end plate 24 being omitted.

Figure il is a diagrammatic view showing the work moving mechanism and its controls.

Figures l2 to l5, inclusive, are diagrammatic views showing the :notion of the work while one lobe and an adiacent iiat are being ground.

Figures i6, 17 and 19,'inclusive, are diagraml Claims. (Cl. 51-95) matic views showing the tool and work motion controls for five, four, and two lobe-shaped grindlines I8-I8 and 2li-2U of Figures 15 and 16, re-

spectively, and are somewhat of Figure 1.

Referring rst to Figures 1, 4 and 5, the Inachine as shown includes a rotary work spindle I having at one end a suitable chuck 2 for the reception of a work piece 3. This work piece may be a piece to be ,internally shaped to lobe form, this being illustrated in Figures 1, 4 and 6 to 15, inclusive, or it may be an external work piece which is to be Amachined on its outer face to lobe form as shown in Figures 6 and 7. The shaft I extends through a pair of internal cams IU, and as these are identical a description of one will be sufficient. It has a portion II provided with an internal arc shaped opening I2 which throughout its full extent is circular. At one side the cam I0 is cut away and the cut away portion is bridged by a plate I5 which presents an internal flat vertical face I 6. The arcuate similar to a portion and flat faces of the two cams are arrangedV identically angularly. Each of these cams may be supported as by a foot 20 from the base 2| ofthe machine. As shown, the flat for the interior of each cam IIJ is formed by the separate plate I5 which is secured as by screws 22 to the arcuate portion. The shaft I is supported within each of these internal cams and to this end it has secured thereto a set of three eccentrics 25, the maximum eccentricities of which are arranged apart angularly around the shaft, and the eccentrics of each set are arranged identically angularly spaced around the shaft. Means such as end plates 23 and 24 retain the eccentrics between the side faces of the cams. In order to reduce frictional drag, these eccentrics 25 are each provided with a circular rim 26 supported in ball bearings 21 and these circular rims may engage with the inner faces of the internal cams.

Means are provided by which the shaft I with the parts carried thereby may be caused to move in a plane transverse to the shaft axis and with at least two of the eccentrics 25 in engagement with the inner faces of each of the two cams, and since the cams and eccentrics are similarly arranged, the motion of the spindle I is limited to motion transverse to its length and with the motion of the work holder or chuck 2 in a plane.

Means are provided by which the spindle I and the parts carried thereby are moved in a closed path guided by the operative engagements l between the eccentrics and the interior walls of the cams. To this end the spindle between the cams l0 is shown in Figure l as provided with spaced disk portions on which are mounted the inner raceways 3| of ball bearings 32. As shown there are two of these disks 30 spaced apart along the length of the spindle and arranged between and adjacent to the inner faces of the cams I0. The outer ball raceways 33 of these ball bearings, as shown best in Figure 2, are carried by annular straps 34 to which are secured in the same planes the bars 35. As shown in Figure 2, the straps 34 are made in two semicircular portions which are secured together as by screws 36. The bars 36 are slidably guided through sleeves 40. As shown each of the sleeves 40 has a pair of spaced ball bearings 4| which slidably support the bars 35. At their rear ends they are joined by a cross bar 42 which is attached through a pivoted link 43 to the rear end of a piston rod 44. This piston rod extends into a hydraulic pressure cylinder 45 positioned between and integral with the sleeves 40 and within this cylinder it carries a piston 46. Cylinder heads 41 and 4B close oif the ends of the cylinder, the head 48 having a suitable gland 46 through which the piston rod 44 extends. The outer end of the cylinder 45 is provided with a pair of spaced depending ears 50 between whichis hinged a flattened portion 5| of a head secured to the upper end of a piston rod 52 which extends into a hydraulic cylinder 53, the lower end of which is pivoted as at 54 to the bed 2|. It will be evident that by admitting hydraulic fluid under pressure to one or the other side of the piston 46 carried by the rod 52, this piston may be moved lengthwise of the cylinder 45 and that likewise by admitting :duid under pressure to opposite ends of the cylinder 53, the piston 56 therein may be driven lengthwise, thus to rock the sleeves 40. By a combination of these motions the work spindle may be moved in a closed path determined by the contour of the internal cam l0. Means may be provided for so controlling these motions as to cause a bodily movement of the spindle and the work carried thereby controlled by the contours of the cams |0. Such means is shown diagrammatically in Figure 1l.

Hydraulic iiuid under pressure is derived from a suitable supply tank 60, being pumped therefrom through a pump 6| into a pressure line 62 from which a relief valve 63 controls discharge back to the tank, thus to limit the pressure in the pipe 62. This pipe 62 leads to a valve casing 65 within which is an axially movable valve 66. This valve may be moved in opposite directions by energization of a pair of solenoids 61 and 68; In the position shown fluid under pressure from the pipe 62 passes through the valve casing 65 through a pipe 10 into the right hand end of the cylinder 45, thus to drive the piston 46 inwardly. Fluid under pressure discharges from the left hand end of the cylinder 45 through the pipe 1| to the valvecasing 65 and back through the discharge line 12. At the same time pressure from the pressure pipe 10 leads through the pipe 13 to the lower left hand end of the cylinder 53 in position to drive its piston 56 upwardly, fluid dis-` charging from the upper end of the cylinder 53 through the pipe 14 into the pipe 1| and past the valve 65 into the discharge pipe 12. This causes the outer end of the cylinder 45, together with the guide sleeves 40, to be lifted while the piston 46 is driven inwardly, thus pressing the spindle downwardly and to the left so that its eccentrics 25 are pressed against the curved faces |6 of the internal cams.

Assume that the cams are to be traversed counterclockwise as viewed from the work holder end of the spindle. At the start of this motion the eccentric straps 34 are at their upper limits of motion impinging upon a switch member which closes a contact at 0|. '-IhisA closes a circuit from the line 82 through one pole 83 of the switch 8|, leads 84, solenoid 85, back to the line 86. Energizing the coil 85 closes the switch 00. The closing of the switch closes a circuit from the line 82 through switch 90 and lead 86 through 'a solenoid 68, lead 63, back to the line 86. This energizes the solenoid 68 and moves the valve 66 to the position shown.

The eiect ofthe fluid pressure to move the piston 46 to the left and to move the piston 56 upwardly and outwardly is to rock the sleeves 40 in such a direction as to lower each strap 34 while therings 26 surrounding the eccentrics are pressed against the internal curved faces of the internal cams and to allow switch 8| to open. deenergizing solenoid 68. This motion of the work takes place until each eccentric strap 34 approaches its lowest position at which time one engages the switch element 9| and closes the switch contacts |00 and |02. The closing of the switch contact |02 establishes 'a circuit from the line 82 through leads |03, switch contact |00,

switch element 9|, contact |02, lead |04, solenoid |05 and leads |86 and 68, back to the line 86. Energization of the solenoid |05 closes the switch |08 which completes a circuit from the lead |03 through the switch |09, the lead ||0, solenoid 61 and lead 69 back to the line 86. This acts to move the reversing valve 66 to its left hand position wherein the pressure line 68 is connected through the pipe 1| to the left hand end of the cylinder 45 while the right hand end of this cylinder is opened to the discharge pipe |I| which connects to the discharge pipe 12. This presses the rings 26 around the eccentrics 25 against the flat faces |6 of the internal cams while at the same time the pressure connections to the cylinder 53 have also been reversed so that the cylinder 45 is rocked downwardly. Thus the effects of the fluid-pressure are to cause the work piece to be brought downwardly while the eccentrics 25 are pressed into .operative engagement with the curved portions of the internal cams, while during the upward stroke these eccentrics are pressed against the straight faces of these cams.

The resultant effects may be understood by referring to Figures 12 to 15 in connection with Figures 8, 9, and l0. In Figures 12 and 8 the work is shown at its upward limit of position and about to move downwardly. In this position two of the eccentrics 25 have their rings 26 bearing against the upper curved portion of the corresponding internal cam i0. These rings 26 are designated as 26a and 26h on Figure 12. The third ring 26e is out of contact with the interior of its internal cam. The grinding wheel which is shown in these diagrams as an internal wheel at W is then in engagement with the lower portion of the at ||5. The axial center of the work spindle is shown at O. As the strap 34 descends while the rings 26a and 2Gb are pressed against the curved face of the cam, the center O of the work piece moves through the path shown by the curved arrow in Figure 13, while the Work piece itself is turned through an angle represented by the angular motion of the space between vthe lines a--b. The Wheel is then in the ward motion continues, the rings 26a and 26h continuing their downward motion in contact with the arcuate face of the corresponding cam until the strap 34 reaches its lowest position shown in Figures 14 and 9,-the lines a--b then assuming the angular position shown in Figure 14 and the center ci the work having described a path shown by the curved arrow. The grinding wheel W has now traversed a lobe of the work from the position shown in Figure 12 to that shown inFigure 14 through the intermediate positions shown in Figures 13 and 10. The work now being in its lowest position'and starting upwardly, the ring 26e and the ring 26h are now pressed into engagement with the at face i6 of the cam as shown in Figure 14, and as the work is moved upwardly these follow up in a straightV path a distance shown by the arrow X of Figure 15 and -from the positions shown in Figures 14 and 9 to the position shown in Figures 15 and 8. It will thus be seen that no turning of the work piece takes place during this upward motion which causes the grinding wheel to generate a flat on the work. In one circuit of the cams, one lobe and one flat have been ground. As the work then is lowered again and its controlling rings 26 are again pressed against the curved faces of the internal cams, the rings 26h and 26o are now in engagement with this curved face, as shown in Figure 15, the ring 26a being then out of control. This cycle continues, each time the curved faces of the cams being engaged by one of the rings previously in engagement therewith and the other ring which was out of engagement with this face during the preceding motion. Thus at the iirst rotation the rings 26a-and 26h are controlling, in the second rotation'the rings 26e and 26h are controlling, and in the third rotation the rings h and 26a are controlling. ItV will be seen, therefore, that at each rotary movement, the work has been turned throughout 120 about one of the lobed portions of the contour and that between these turning motions the grinding wheel is effective to grind the ats between the lobes. In three circuits around the cams, one complete contour of the work has been ground, the work describing a circular curved path while being turned, Vand a straight path joining the ends of the circular path without turning.

The same action takes place when external work is being ground, as is shown vin Figures 6 and '7, except that the wheel W is fed in the opposite direction against the outside of the work rather than being fed against the inside face of 'the work as is necessary for the internal grinding. Suitable means, not shown herein but well known in the art, may be employed to support the grinding wheels for feeding with reference to the work and for truing them as occasion demands.

The general arrangement hereinbefore described is applicablewith certain modications to the cutting or grinding of any lobed form havingan odd number of lobes, it being necessary only that there be provided equally angular- 1y spaced eccentrics in number equal to the number of lobes, and that the curved portion of the cam path is of the proper angular extent to cause turning of the work spindle through the proper angular extent for the number oi lobes.

Thus in Figure 16 there is shown diagram-- matically mechanism for grinding five-lobed forms. The number' of eccentrics with their externally iournaled rings is ve, the rings beingf by 'one after each cycle of grinding of one lobe` and one fiat corresponding to one complete traverse around the inner face of the internal cam.

If it be attempted to cut a form with an even' number of lobes, the same number of eccentrics' as lobes cannot be used, however, as if this be attempted Van unstable condition Aarises so that positive control of the angular position of the work spindle at all times is not aiorded. How-l ever, by employing twice the number of eccentrics as lobes, positive control can be had but certain changes have to be made to prevent interference of parts as will now be pointed out.

Figures 17 and 19 show diagrammatically by views similar to Figure 16, an arrangement for grinding four and two lobed forms, respectively,

and Figures 18 and 20 show in section the corresponding parts. The eccentrics and rings are arfranged in two sets', one set comprising theV rings 26a, 26h, 26o and 26d, and the other the rings 260e, 268i), 26Go and 2601i.

In the position shown in Figure 17, the two rings 26a and 26d contact with the iiat cam face i 5 and as the work piece is moved vertically, this contact prevents rotation of the work spindle. From an inspection of Figure 17, it will be evident, however, that when the work spindle reaches its limiting position for grinding a iiat,

only one of the rst set of rings, as 2Gb, is in engagement with the curved portionof the inter-A nal cam. Thus the angular position of the spindle cannot be controlled by this engagement, and

the necessary positive turning of the spindle for grinding the lobe curvature cannot be produced.

In order to provide for positive turning control of the spindle, the second set of four eccentrics with journaled rings 269e, 266D, 2600 and 26M is provided, these eccentrics being positioned intermediate in angular positions to the eccentrics and rings 26a, 2Gb, 26e and 26d. At Vthe end of the stroke of the work spindle along the at I6, two oi these rings 260er and 26M) are in contact with the arcuate face I2 and these act togetherV to positively control and turn the spindle `through before the next traverse of the flat I6. It will be noted, however, that when the tworings 26d and 26a engage the flat, the ring 2Std, as shown in dotted lines in Figure 17, will project beyond the flat. it is thus necessary to position the eccentrics and rings 26M to 26M where theyareV out of line with the fiat I6, if the arcuate portien traversed by these rings is to be of the same i diameter as that traversed by the rings of the first set. The second set of rings, therefore, are shown axially oir-set from the first set of rings in a chamber |59 which may, however, have its arcuate face formed as a continuation-0f;-

the arcuate face i2, and in any event it is concentric therewith. whether or not itis of the same diameter, and this chamber E50 is extended on the side corresponding to the flat face I5 so as to lprovide room for the passage of the rings of the During the traverse lof second set while rings of the iirst set are guiding the Work spindle for non-rotating but bodily traversing motion.

Similarly where two-lobed forms are to be prepared, there will be two sets of eccentrics and rings, the rings 26a and 2Gb of one set engaging the dat i6 at certain times. When grinding the lobes while the arcuate face I@ is controlling the turning of the spindle, one of the rings of the second set and one of the rings of the rst set together engage the arcuate face. Here, again, the second set of rings is arranged offset axially from the rst and out of the general plane of the flat face I6 beyond which they would have to extend provided that all the rings are the same size, and the curved face portion of the internal cam with which they engage is an axial continuation of the arcuate face engaged by the rings of the iirst set.

In al1 cases it Will be noted that the arcuate portion of the internal cam is of such an extent that the angular turning of the spindle is the reciprocal of the number of lobes, that is, for twolobed forms each turning is half a revolution, and for three-lobed forms each turning is one-third of a revolution, etc. It will be noted that the cutting action takes place throughout a closed path and either on the inside or outside peripheries thereof.

In all cases, also, the end face of the rotary tool may be employed in facing the work or in forming shoulders on external work against which the parts carried by the lobed shafts may be seated.

From the foregoing description of an embodiment of this invention it should be evident to those skilled in the art that various changes and modiiications might be made without departing from its spirit or scope.

I claim:

1. A machine of the class described, comprising a work holder, means supporting said work holder for motion in a plane, means limiting the motion of said Work holder comprising an internal cam having an arcuate portion and a straight portion joining the ends of said arcuate portion, means including a multiple-point support movable with said work holder for engagement with the cam face of said cam, means moving said support in one direction around said cam contour with at least two of said supporting points in engagement with said cam atall times, and a tool positioned to engage a work piece carried by said holder while said holder is being so moved.

2. A machine of the class described, comprising a rotary work spindle, a work holder carried at one end of said spindle, a pair of similar internal cams spaced along said spindle, three eccentrics xed to said spindle and operatively engaging the inner faces of each of said cams, said eccentrics having their maximum eccentricities spaced from each other by 120, each of said cams having a circular curved portion and a iiat joining the ends of said curved portion, the curved portions and flats being similarly angularly arranged on both cams, means engaging said spindle between said cams and moving said spindle in a closed path with said eccentrics moving around the inner faces of said cams, and a tool positioned to operate on work carried by said work holder during the motions of said spindle in said closed path.

3. A machine of the class described, comprising a rotary work spindle, means rotatably supporting said spindle comprising a pair of closed set of three eccentrics xed to said spindle within' each cam, the eccentricities of the eccentrics of each set being spaced angularly by 120, each of said cams having an arcuate portion and a flat joining the ends of said arcuate portion, means for moving said spindle in a closed path with two of the eccentrics of each set operatively engaging its internal cam at all times, and a tool in l0 as said spindle is so moved.

4. In a machine of the class described, a rotary work spindle, means rotatably supporting said spindle comprising a pair of closed internal cams spaced along said spindle and a set of three eccentrics iixed to said spindle within each cam, the eccentricities of the eccentrics of each set being spaced angularly by 120, each of said cams having an arcuate portion and a flat joining the ends of said arcuate portion, a ring within which said spindle is j ournaled. a bar iixed to said ring, a sleeve through which said bar is slidably mounted, means pivotally supporting said sleeve, and means actuable to move said bar through said sleeve and to rock said sleeve in time therewith to cause said eccentrics to be moved around in operative contact with said cams in a closed path.

5. A machine of the class described for tooling a workpiece to a contour having an odd number of lobes symmetrically disposed about its axis, comprising a rotary work spindle, a work holder carried by said spindle for supporting said work piece with said axis parallel to the axis of said spindle, an internal cam arranged transverse to the axis oi said spindle and having an arcuate portion and a flat joining the ends oi' said arcuate portion, a plurality of eccentrics xed to said spindle one for each lobe and arranged equally angularly spaced about the axis of said spindle and in position to operatively engage the'inner face of said internal cam, means engaging said spindle and moving said spindle in a closed path with at least two of said eccentrics in operative contact with said internal cam, the arcuate portion of said cam being of such an extent as to cause said shaft to rotate through that fraction of a revolution denoted by the reciprocal of the number of said lobes during each complete ciryicuit of said spindle within said closed path, and a tool positioned to operate on work carried by said work holder during the motions of said spindle in said closed path.

6. A machine for tooling a Work piece to a contour having an even number of lobes symmetrically disposed about an axis, comprising a rotary work spindle, a work holder carried by said spindle supporting said work piece axis parallel to the axis of said spindle, an internal cam having an arcuate portion and a flat joining the ends of said arcuate portion, a plurality of eccentrics fixed to said spindle and spaced equally angularly therearound, there being twice as many eccentrics as lobes of said work piece -2and said eccentrics being arranged in two sets alternately around the axis of said spindle, all of the eccentrics of one set being in position to operatively engage the inner wall of said cam, an arcuate wall concentric with said arcuate cam portion and against which the cams of the other of said sets may operatively engage, means engaging said spindle and moving said spindle inv a closed path with at least two of said eccentrics operatively engaging at all times with either said `internal cam or said arcuate wall, the arcuate operative relation to work carried by said spindle portion of said cam and Wall being of such extent as to cause said shaft to rotate that fraction of a revolution denoted by the reciprocal of the number of said lobes during each motion of said spindle in a complete circuit of said closed path, and a tool positioned to operate on work carried by said Work holder during the motions of said spindle in said closed path.

7. A machine of the class described, comprising a rotary Work spindle, means rotatably supporting said spindle comprising a pair of closed internal cams spaced along said spindle and a set of three eccentrics fixed to said spindle within each cam, the eccentricities of the eccentrics of each set being spaced `angularly by 120, each of said cams having an arcuate portion and a at joining the ends of said arcuate portion, a ring Within which said spindle is journaled, a bar Xed to said ring, a sleeve through which said bar is slidably mounted, means pivotally supporting said sleeve, means actuable to move said bar through said sleeve and to rock said sleeve in time therewith to cause said eccentrics to be moved around in operative contact With said cams in a closed path, and a tool positioned to act upon Work carried by said holder during the motions thereof.

MERTON H. ARMS.

REFEREN CES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

